I will classify the castles in order of difficulty and by "family of castles". This classification is of course subjective and a castle may seem easier to you while I find it harder and vice versa. Absolutely all AI castles can be taken at once, except the 3 biggest wolf castles, 8, 9A and 9B (and again, there may be players who can do 8 and 9A in one wave).
My standard army, which I stock in all my vassals, consists of 300 archers, 150 pikemen and 50 catapults.
I will talk in this tutorial about side 1 for the bottom left side, 2 for the top left side, 3 for the top right side and 4 for the bottom right side (1lower left in front of the entrance of the fort and then turn clockwise).